Total mixed service costs
(6) Definition of total mixed service costs. Total mixed service costs are defined as the total costs incurred during the taxable year in all departments or functions of the taxpayer's trade or business that perform mixed service activities. See paragraph (e)(4)(ii)(C) of this section which defines mixed service costs. In determining the total mixed service costs of a trade or business, the taxpayer must include all costs incurred in its mixed service departments and cannot exclude any otherwise deductible service costs. For example, if the accounting department within a trade or business is a mixed service department, then in determining the total mixed service costs of the trade or business, the taxpayer cannot exclude the costs of personnel in the accounting department that perform services relating to non-production activities (e.g., accounts receivable or customer billing activities). Instead, the entire cost of the accounting department must be included in the total mixed service costs. (7) Costs allocable to more than one business. To the extent mixed service costs, labor costs, or other costs are incurred in more than one trade or business, the taxpayer must determine the amounts allocable to the particular trade or business for which the simplified service cost method is being applied by using any reasonable allocation method consistent with the principles of paragraph (f)(4) of this section. (8) De minimis rule. If the taxpayer elects to apply the de minimis rule of paragraph (g)(4)(ii) of this section to any mixed service department, the department is not considered a mixed service department for purposes of the simplified service cost method. Instead, the costs of such department are allocated exclusively to the particular activity satisfying the 90-percent test. (9) Separate election. A taxpayer may elect the simplified service cost method in conjunction with any other allocation method used at the trade or business level, including the simplified methods described in 1.263A-2(b) and (c) and 1.263A-3(d). However, the election of the simplified service cost method must be made independently of the election to use those other simplified methods. (i) [Reserved]